September 2021
Volume 21, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2021
Exogenous Shifts of Spatial Attention Operate at a Finer Resolution than Endogenous Shifts
Author Affiliations
  • Chris Reynolds
    University of Wisconsin-Milwaukee
  • Adam Greenberg
    University of Wisconsin-Milwaukee
    Medical College of Wisconsin and Marquette University
Journal of Vision September 2021, Vol.21, 2790. doi:
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      Chris Reynolds, Adam Greenberg; Exogenous Shifts of Spatial Attention Operate at a Finer Resolution than Endogenous Shifts. Journal of Vision 2021;21(9):2790.

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      © ARVO (1962-2015); The Authors (2016-present)

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Shifts of visuospatial selective attention are limited in spatial resolution (i.e., the necessary spacing between a selected target and distractors; Intriligator & Cavanagh, 2001). Previous research on attention resolution has focused on endogenous selection. Our goal was to measure the resolution of exogenous shifts of visuospatial attention by quantifying the minimum spacing needed for individuals to isolate and select a peripheral item among nearby distractors. In Experiments 1 & 2 (peripheral stimulus diameters of 1° or 0.75°, respectively) participants viewed a circular array of equally spaced, luminance-matched colored disks at 10° eccentricity on a median gray background with a single white RSVP stream at fixation. Subjects monitored RSVP items for one or more target digits and responded via button press. Simultaneously, on each trial a black dot briefly (60 msec) appeared (among the peripheral-colored disks) which exogenously captured attention. After each trial, participants selected via mouse-click the color (from several choices) corresponding to the location nearest to which the black dot had appeared on that trial. Participants in Experiment 2 (M = 49.54%) performed significantly better than participants in Experiment 1 (M = 37.4%) on the color selection task. Responses were compared to an ideal observer model to determine the size of attentional window each subject deployed in response to the exogenous cue. This window size was then used to quantify the minimum stimulus spacing needed for performance to reach 75% correct. Minimum spacing estimates were not significantly different either between Experiment 1 (M = 1.076°) and Experiment 2 (M = 1.051°) or within-subject (across the visual field). These results are 24% (Experiment 1) and 26% (Experiment 2) less than the magnitudes reported in endogenous attention investigations. We conclude that the spatial resolution of exogenous attention shifts allows for a finer grain of selection compared to that of endogenous shifts.


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